High-frequency electric separator



NOV. 8, 1949 w, PRlCE 2,487,272

HIGH-FREQUENCY ELECTRI C SEPARATOR Filed May 24, 1946 w/ INVENTOR L160? G. PRICE:

BYQ a n ms ATTORNEY Patented Nov. 8, 1949 HIGH-FREQUENCY ELECTRIC SEPARATOR William G. Price, Port Blakely, Wash.

Application May .24, 1946, Serial No.'671,978

3 Claims. (Cl. 209-212) My invention relates to the separation of particles of non-magnetizable electrically conductive materials such as gold, silver and copper from non-metallic particles such as ground rock and sand.

The invention has for its object the provision of a means and a method of separating materials of the character referred to, by the use of a high frequency electrical current field through which the mixture of materials is passed in the form of a stream and in such manner that movement of the electrically-conductive particles is so retarded by the field that they fall from the moving stream under the force of gravity.

In the accompanying drawing, Figure 1 is a side view, partly in section, showing apparatus suitable for use in the practice of my invention; Fig. 2 is a schematic plan view of a portion of the apparatus of Fig. 1, and Fig. 3 is a perspective view, on an enlarged scale, of a portion of the electrical coil of Figs. 1 and 2.

The apparatus comprises a base 4 to which is secured a frame 5 in which shafts 6 and l are journaled, the shaft 6 being driven at high speed from any suitable source of power to thereby rotate the shaft I and a table 8 that is secured to the shaft 1. A plate 9 is supported from the base 4 by uprights I and has bins l I, I2 and [3 formed therein in position to receive particles of material projected from the table 8.

Finely divided dry materials such as ground rock containing metal particles or sand with metal particles are supplied to the table 8 by any suitable means such as a conveyor belt l that discharges upon a screen 5 to separate the coarsest particles from the fine particles that will fall into a hopper l7 whose lower end is positioned in proximity to a comically-shaped boss It at the center of the table.

The material is fed at such rate and the table rotated at such speed that the particles of the mixture will be discharged by centrifugal force from the edge of the table in a thin stream or sheet of a thickness not substantially greater than the diameter of single particles. To this end, the table, if its surface is at an angle of approximately 14 to a horizontal plane, will suitably be rotated at about 400 revolutions per minute. The material will be fed from the hopper at a rate depending upon the diameter of the table so as to maintain the desired thinness of the stream or sheet discharged from the edge of the table.

An alternating magnetic field is produced by a high frequency generator 20 at perhaps 30,000

volts and a frequency of 18 mgc. The high-frequency field is produced in a zone extending peripherally of the table by a coil 2| that may suitably be in the form of copper tubingjone portion of which is bent to form a lower loop 22 that extends the complete distance around the table, except for the small space shown in Fig. 3, and an upper loop 23 that also extends completely around the table, except at said space, the tube being bent at 24 where the loops 22 and 23 meet. The free end of each loop is extended laterally at 25 and 26 respectively, for connection with the generator 20. An electrical field as indicated at 21 is thus produced entirely around the peripheral edge of the table.

The vertical spacing of the loops 2223 of the coil and their positions are such that the particles will be discharged from the table through the space between loops and hence through the middle of the field 21. Because an alternating field resists the passage therethrough of electrically-conductive but non-magnetic material, the movement of the metallic particles when discharged from the table will be retarded, causing them to drop into the bin ll, under the force of gravity. The less conductive particles will fall into the bin [2, while the non-conductive particles will fall into the bin l3. Because the mixture is discharged in the form of a stream of single-particle thickness, danger of the metallic particles being pushed over into the bin [3 by the non-metallic particles is reduced to a minimum.

I claim as my invention:

1. An electrical separator comprising a table that is rotatable in a horizontal plane, to centrifugally discharge finely divided material that is supplied to a, central zone thereon, an electric coil disposed adjacent to the edge of the table, but spaced peripherally thereof, and means for supplying an alternating electrical current of high frequency to the coil, of sufiicient intensity to provide a field that will be effective to retard movement of any electrically-conductive but nonmagnetic particles when they are discharged from the table, the coil having a loop positioned to lie beneath the stream of material discharged from the table and a loop'positioned above the other loop and above the stream.

2. An electrical separator comprising a table that is rotatable in a horizontal plane, to centrifugally discharge finely divided material that is supplied to a central zone thereon, an electric coil disposed adjacent to the edge of the table, but spaced peripherally thereof, and means for supplying an alternating electrical current of high frequency to the coil, of suflicient intensity to provide a field that will be effective to retard movement of any electrically-conductive but nonmagnetic particles when they are discharged from the table, the material-receiving surface of the table being sloped upwardly from its center to its peripheral edge, the coil having a loop positioned to lie beneath the stream of discharged material and a loop above the other loop and above the stream.

3. An electrical separator comprising means for projecting a mixture containing electrically-conductive but non-magnetic particles and non-conductive particles, in a generally horizontal direction and in the form of an unsupported thin stream, an electric coil having a loop positioned in a plane below the plane of the stream, and a REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 653,342 Gates July 10, 1900 1,417,189 McCarthy May 23, 1922 1,422,026 Brown July 4, 1922 1,829,565 Lee Oct. 27, 1931 

